The present invention relates generally to vehicle steering axle assembly components and more particularly to a new and improved steering knuckle for vehicle steering axles.
Steering knuckles have been used in vehicles for quite some time. Steering knuckles are a component part of vehicle steering axle assemblies, including those axle assemblies used in automobiles and in commercial light-, medium- and heavy-duty trucks. Steering knuckles are associated with the steering axle of such vehicles and function to provide a mount for the spindle or hub of a vehicle wheel. Generally, steering knuckles are controlled directly by the steering linkage system of vehicles.
FIG. 1 illustrates a typical vehicle steering axle assembly generally designated by reference numeral 20 having a plurality of component parts. Steering axle assembly 20 includes an axle beam 22 that extends laterally across a vehicle. At its end portion, axle beam 22 includes a king pin bore 24.
Vehicle steering axle assembly 20 also includes a steering knuckle/spindle 28 having a steering knuckle portion 30 with an integrally forged spindle portion 32. Steering knuckle portion 30 includes upper and lower king pin bores 34, 36, which are coaxially aligned. Steering knuckle portion 30 also includes a steering arm mounting bore 38 and a tie rod arm mounting bore 40.
As shown, a steering linkage system of the vehicle typically includes a steering arm 42 that is connected to steering knuckle/spindle 28 when an end of the steering arm is received and fastened in steering arm mounting bore 38 by a fastener assembly 44. A draglink 46, at one end, is connected to steering arm 42 by a fastener assembly 47. The other end of draglink 46 is connected to a steering control box (not shown) for effectuating steering control of the vehicle.
As further shown, conventional steering linkage systems also include a tie rod arm 48 that is connected to steering knuckle/spindle 28 when an end of the tie rod arm is received and fastened in tie rod arm mounting bore 40 by a fastener assembly 50. Tie rod arm 48 converts torque to a tie rod end 52, which is connected thereto. Tie rod end 52 includes the ball portion of the tie rod linkage and transfers force to a crosstube 54, which is connected thereto. Crosstube 54 connects to a tie rod end associated with another steering knuckle positioned on the opposite side of the vehicle at the opposite end of axle beam 22 and transmits a force between the two wheel ends. This allows steering to be effectuated on both sides of the vehicle. Preferably, crosstube 54 has an adjustable thread to set front axle toe to a specified amount.
A king pin 56 is also included to attach steering knuckle/spindle 28 to axle beam 22. King pin 56 defines a steering axis pivot for vehicle steering axle assembly 20. King pin 56 extends through the upper and lower king pin bores 34, 36 of steering knuckle/spindle 28 and through the king pin bore 24 of axle beam 22. As shown, a bushing 58 is positioned between the inside surface of king pin bore 34 and king pin 56. Similarly, a bushing 60 is positioned between the inside surface of king pin bore 36 and king pin 56. Bushings 58, 60 permit steering knuckle/spindle 28 to pivot about king pin 56 during vehicle steering. As further shown, a gasket 62, a cap 64, multiple capscrews 66 (one being shown at each end) and a grease fitting 68 are included for each of the upper and lower king pin bores 34, 36 of steering knuckle/spindle 28.
Still referring to FIG. 1, a plurality of shims 70 are typically included to establish the desired spacing between steering knuckle/spindle 28 and axle beam 22 when the parts are assembled. Furthermore, several draw keys 72 are also typically included to hold king pin 56 in place in axle beam 22 during operation. King pin 56 includes notches 73 for receiving draw keys 72. Furthermore, axle beam 22 includes draw key holes (not shown). It will be appreciated by those skilled in the art that king pin 56 would slidably move freely within king pin bore 24, if not for draw keys 72 holding it in place.
As further shown, the spindle portion 32 of steering knuckle/spindle 28 is blended and/or tapered at its root where it integrally connects with the steering knuckle portion 30 of the steering knuckle/spindle. The blended root construction increases the stress tolerance of spindle portion 32. Due to high bending stresses resulting from side loads during vehicle cornering, spindle portion 32 must typically be constructed of a high strength, premium steel. In the case where an integrally forged spindle 32 is used, the entire steering knuckle/spindle 28 is forged from high strength steel.
Still referring to FIG. 1, a wheel hub 74 having a centrally disposed wheel hub bore 76 is positioned over spindle portion 32 of steering knuckle/spindle 28 and secured in that position so that the spindle portion extends through the wheel hub bore. Wheel hub 74 allows for mounting of the vehicle wheel (not shown), which is positioned on the end of axle assembly 20 shown in FIG. 1. A cylindrical brake drum 78 having a centrally disposed brake drum bore 80 is positioned over wheel hub 74 and secured in that position. Brake drum 78 allows the brake shoes (not shown) to press against it, causing friction, which, in turn, stops rotation of the vehicle wheel positioned on its end of the steering axle assembly.
FIG. 2 illustrates the assembly and/or service of a conventional steering knuckle 28 to an axle beam 22 with a king pin 56. FIG. 2 is included herein to illustrate some of the problems associated with the assembly and service of conventional steering axle assemblies 20. The present invention completely eliminates those problems.
As shown in FIG. 2, and referring also to FIG. 1, the upper and lower kingpin bores 34, 36 of steering knuckle/spindle 28 must first be brought into registration with the kingpin bore 24 of axle beam 22. King pin 56 is then inserted through bore 34, bore 24 and bore 36 and held in place in axle beam 22 by draw keys 72.
Because their steering pivot axis (king pin) bores are positioned on the same piece, conventional steering knuckles, such as steering knuckle/spindle 28 shown in FIGS. 1 and 2, make use of a press in king pin impractical, and use of a king pin fixed within the axle beam impossible. Conventional steering knuckles require the axle beam king pin bore to allow the king pin to slide therein. As such, the axle beam king pin bore provides for a loose fit to allow the king pin to be inserted through it during assembly and service. This loose fit is a leading reason for failure of the axle beam. In particular, sliding movement of the king pin within the axle beam king pin bore over time can cause wear in that bore and cause the fit to loosen further than desired. Additionally, moisture can enter the cylindrical space between the king pin and the axle beam king pin bore, causing the king pin to be frozen in place and incapable of being removed. Under such circumstances, the steering knuckle cannot be serviced, absent practical destruction of same. In particular, the steering knuckle/spindle cannot be removed from the king pin when the king pin is frozen or otherwise stuck in the axle beam king pin bore.
Conventional steering knuckles also require draw keys to hold the king pin in place in the axle beam. The use of draw keys increases the components of the steering axle assembly, which, in turn, adds cost and weight to the assembly. In the case of commercial vehicles, this additional weight translates into reduced payload capacity.
Another deficiency of conventional steering knuckles is that any desired vertical spacing between the upper and lower sections of the steering knuckle and the end of axle beam must be provided by shims or similar components. These additional components add weight and cost to the steering axle assembly, which, in the case of commercial vehicles, translates into reduced payload capacity.
Still another deficiency of conventional steering knuckles is that they do not allow for alignment adjustment when fitting to the end of an axle beam.
Another deficiency of conventional steering knuckles is that the knuckle king pin bores and the axle beam king pin bores must all be precision-machined so that they are coaxially aligned when positioned in registration with each other. Without precision-machined bores, the king pin cannot be inserted through the bores and removed from them, as necessary, during assembly and service. In a related manner, the bores must be precision aligned during assembly and service of the steering axle assembly. These stringent requirements make the assembly and service processes for the steering axle assembly cumbersome.
As described above, those conventional steering knuckles that have an integrally forged spindle typically must be constructed in their entirety of high strength, premium steel due to the bending stress caused by side loads resulting from vehicle cornering. The steel used is relatively expensive and is difficult to machine, which further increases the manufacturing costs of those steering knuckles. Furthermore, those steering knuckles typically must have a blended root to accommodate the bending stress. The blended root conventionally has stringent demands on its surface finish, else its useful life is compromised. As a result of the stringent requirements, the manufacturing process is typically difficult to carry out and requires a substantial amount of time and labor which translates into relatively expensive manufacturing costs.
Another deficiency of conventional steering knuckles is that they typically include steering arms and tie rod arms that must be fastened thereto with a plurality of separate machined interfaces and fasteners devoted exclusively to fastening the arms to the knuckle. Manufacturing and assembly of these components adds cost and weight. Furthermore, use of separate steering arms and tie rod arms can create packaging problems for the steering axle assembly. In particular, conventional steering knuckles that have separate steering arms and tie rod arms cannot ordinarily be used with so-called fabricated axle beams, which are made of sheet metal.
Yet another deficiency of conventional steering knuckles is that they are difficult to machine. Most notably, conventional steering knuckles require multiple clampings to carry out the many machining operations. This increases the cost associated with their manufacture.
In light of the foregoing, it is desirable to design a vehicle steering axle steering knuckle that will overcome one or more of the above-identified deficiencies of conventional steering knuckles.
It is also desirable to design a steering knuckle for use in association with a vehicle steering axle that facilitates the assembly and service problems associated with conventional steering knuckles.
It is further desirable to design a steering knuckle that reduces the cost and weight associated with the manufacture and assembly of conventional steering knuckles.
These and other objects of the preferred forms of the invention will become apparent from the following description. It will be understood, however, that an apparatus could still appropriate the invention claimed herein without accomplishing each and every one of these objects, including those gleaned from the following description. The appended claims, not the objects, define the subject matter of this invention. Any and all objects are derived from the preferred forms of the invention, not necessarily the invention in general.
The present invention is directed to a vehicle steering knuckle for use in association with a vehicle steering axle assembly. The steering knuckle of the present invention includes a first piece having a first steering pivot axis bore extending through it and a second piece removably connectable to the first piece. The second piece has a second steering pivot axis bore extending through it.
There are several additional novel features and aspects of the present invention. Those features and aspects are described in the following description.